MicroLogic Active Real-Time Measurements
Presentation
MicroLogic Active control units measure or calculate in real time the electrical quantities described in MicroLogic Active Measurement Availability and Display.
The values of the electrical quantities, whether measured or calculated in real time, update once a second at rated frequency.
Measuring the Neutral Current
MicroLogic Active control units in 4-pole circuit breakers or 3-pole circuit breakers with the ENCT wired and configured, measure the neutral current:
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For a 3-pole circuit breaker, the neutral current is measured by adding a current transformer on the neutral conductor for the transformer information. For more information, refer to MasterPacT MTZ Catalog.
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For a 4-pole circuit breaker, the neutral current is measured systematically.
The neutral current is measured in the same way as the phase currents.
Measuring the Ground-Fault Current
MicroLogic Active control units calculate or measure the ground-fault current in the same way as the phase currents, according to the circuit breaker configuration, as shown in the following table.
|
Circuit breaker configuration |
Ig ground-fault current |
|---|---|
|
3P |
Ig = I1 + I2 + I3 |
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4P |
Ig = I1 + I2 + I3 + IN |
|
3P + ENCT |
Ig = I1 + I2 + I3 + IN (ENCT) |
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3P or 4P + SGR |
Ig = ISGR |
Measuring the Phase-to-Neutral Voltages (MicroLogic Active E/EP)
MicroLogic Active control units in 4-pole circuit breakers, or 3-pole circuit breakers with the ENVT wired and configured, measure the phase-to-neutral (or line-to-neutral) voltages V1N, V2N, and V3N:
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For a 3-pole circuit breaker, it is necessary to:
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Connect the wire from the ENVT to the neutral conductor
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Declare the ENVT in the system type setting
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For 4-pole circuit breakers, the phase-to-neutral voltages are measured systematically.
The phase-to-neutral voltages are measured in the same way as the phase-to-phase voltages.
Calculating the Average Current
MicroLogic Active control units calculate the average current Iavg, the arithmetic mean of the 3 phase currents:
Calculating the Average Voltage (MicroLogic Active E/EP)
MicroLogic Active E/EP control units calculate the average voltages:
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Phase-to-phase Vavg, the arithmetic mean of the 3 phase-to-phase voltages:
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Phase-to-neutral Vavg, the arithmetic mean of the 3 phase-to-neutral voltages (4-pole circuit breakers or 3-pole circuit breakers wired and configured with the ENVT):
Measuring the Current Phase Unbalance (MicroLogic Active E/EP)
MicroLogic Active control units calculate the current unbalance for each phase (3 values) and the maximum current unbalance.
The current unbalance is a percentage of the average current:
Measuring the Voltage Phase Unbalance (MicroLogic Active E/EP)
MicroLogic Active E/EP control units calculate:
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The phase-to-phase voltage unbalance for each phase (3 values) and the maximum of 3 phase-to-phase voltage unbalances.
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For 4-pole circuit breakers or 3-pole circuit breakers wired and configured with the ENVT: the phase-to-neutral (if present) voltage unbalance for each phase (3 values) and the maximum of 3 phase-to-neutral voltage unbalances.
The voltage unbalance is expressed as a percentage compared to the average value of the electrical quantity (Vavg):
Maximum/Minimum Values
The MicroLogic Active control unit determines the maximum (MAX) and minimum (MIN) value reached by some electrical quantities for the period from the last reset to the present time. The maximum and minimum values available are described in MicroLogic Active Measurement Availability and Display.
Resetting Maximum/Minimum Values
Maximum and minimum values can be reset on the MicroLogic Active display screen from the tree navigation menu:
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Maximum values of current and power can be reset at:
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(MicroLogic Active E/EP)
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Maximum and minimum values of voltage and frequency can be reset at:
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(MicroLogic Active E/EP)
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(MicroLogic Active E/EP)
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